Penitentes, or nieves penitentes (Spanish for “penitent-shaped snows”), are a snow formation found at high altitudes. They take the form of tall thin blades of hardened snow or ice, closely spaced with the blades oriented towards the general direction of the sun.

The name comes from the resemblance of a field of penitentes to a crowd of people kneeling, as when doing penance. The name refers to the tall, pointed habits and hoods worn by brothers of religious orders in the Procession of Penance of the brotherhood to which they belong in Spain, in the processions of Spanish Holy Week. In particular the hats are very tall, narrow, and white with a sharp tip.